The present invention relates generally to a rotary machine. More particularly, the present invention relates to a two-lobe rotor rotary machine having fixed guide members for positioning the rotor apices while rotating a shaft or for being driven by a rotating shaft.
The concept of rotary machines operating as positive displacement machines, e.g., either pumps or engines, date back for several hundred years. For example, U.S. Pat. No. 1,340,625 teaches a rotary machine having a two-lobe lenticular rotor provided with two slots. One of these is in line with the rotor apexes and the other is perpendicular to this and has a center passing through the rotor center which engage fixed guide members mounted on the machine housing. The slotted rotor construction requires that the machine""s rotating shaft be supported completely from one side of the rotor. However, for high torque and high speed rotary machines, considerable stresses necessitate that the single shaft support bearing be substantial, i.e., heavy. In addition, the configuration offered an advantage over the gear in the fabrication but was not more compact in size.
In U.S. Pat. No. 4,300,874, a rotary machine includes a slotted rotor for engagement with a large single guide member and a rectangular portion of the shaft that passes therethrough. A first slot accommodates the guide member and a second slot perpendicular to the first slot accommodates the rectangular portion of the shaft. The rotor slidingly contacts the guide member and the rectangular portion of the shaft during eccentric rotation. However, centrifugal forces from the eccentric motion of the rotor are transmitted in alternate fashion between the guide member and the rectangular portion of the shaft thereby causing forces to be concentrated at the various points of contact. This is the source of friction and wear as rotational speed increases.
The applicant""s prior U.S. Pat. No. 5,393,208 disclosed a rotary machine having a two-lobe lenticular rotor assembly. The rotor has two slots at right angles passing through the center of the rotor however there is a bole through the central portion thereof creating the appearance of four slots cut in one end of the rotor in a symmetric arrangement about the center of the rotor. A rotor guide assembly is provided with two guideposts that engage the slots during eccentric rotation of the rotor assembly. A shaft is provided which passes through the hole in rotor positioning mechanism. This type of rotor positioning mechanism has no contact stresses while operating at a rotational speed in a vacuum while having the rotor supported by a shaft which passes through the rotor positioning mechanism.
It is recognized that an engine of a more compact size in a durable configuration would be useful. Some useful criteria are to have the surfaces of the engine exposed to working medium that have sliding contacts with no force interactions and to have a higher displacement volume compared to the total volume of the machine. The creation of a rotor positioning mechanism operating with only a pressure seal at the side of the rotor and lubrication seals on the shaft was a primary goal of this effort. This concept combined with the longer stroke allows for a device that can replace turbo machinery in many applications.
It has also been recognized that a cyclic thermodynamic process as is possible with piston configurations are inherently more efficient in many instances. This would be found to be the case, for example, if one were to compare the air standard Brayton cycle to the modified Otto cycle having full expansion to the inlet pressure.
The present invention provides for a two-lobe rotary machine capable of functioning either as a pump, engine, or impellor. The improvement for the two-lobe rotary machine allows for a larger shaft to be used for a given sized rotor, or a smaller rotor for a given sized shaft.
The improvement can also be used to increase the volume that may be displaced by the rotary machine as compared to the overall size and mass of the rotary machine, since the rotor crank length or stroke is increased. This results in a rotor assembly that allows the machine to be more compact than if used with internal gears or slots at right angles to keep the rotor apexes in proximity of the inner portion of the outer housing. The machine will thus operate at lower pressure differentials for a given amount of torque on the shaft.
The rotor may also act as an impellor for liquids or gases when not fully enclosed in a housing.
The invention will become more apparent in the following description and drawings.
The present invention provides a rotary machine comprising: a housing with spaced apart end walls for defining a chamber; an elliptical or lenticular two-lobe rotor assembly having curved faces meeting at symmetrically opposed apexes or two lobe rotor with curved faces transitioning to fluidic or aerodynamic surfaces, said rotor assembly having two parallel end faces extending between said curved faces, each of said parallel end faces facing one of said end walls, said rotor assembly disposed in said chamber for eccentric rotation therein, said rotor assembly having a hole in a central portion of the rotor assembly and a shaft having a shaft center longitudinal axis, said shaft center longitudinal axis being offset from said rotor assembly center longitudinal axis by an offset distance RC1, said shaft including at least one eccentric bearing for forming driving contact between said shaft and said rotor assembly;
a rotor with an even number of twelve or more straight cam surfaces arranged about a rotor assembly center longitudinal axis; the straight cams having orientation such that half the straight cam surfaces radially oppose the remaining straight cam surfaces;
straight edges being parallel to line perpendicular to longitudinal axis of eccentric portion of shaft at a distance of Rp;
a rotor guide assembly extending from at least one of said end walls, the rotor guide assembly having six or more arc shaped cams, half of said arc shaped cams radially oppose remaining arc shaped cams, a distance from said shaft center longitudinal axis to each of said arc center longitudinal axes being equal to an offset distance RC2, said rotor guide member assembly including cam surfaces extending in parallel fashion through one of said parallel end faces for engagement with said twelve or more straight cams during said eccentric rotation of said rotor assembly, each of said guide members having a surface with a partially circular perpendicular cross-sectional shape over a portion thereof which engages said straight cam, rotor guide member assembly having approximately half of guide member arcs radially opposing remaining guide member arcs, both sets of opposing guide member arcs having maximum angle between adjacent circular arc longitudinal center of less than 180 degrees;
wherein each of said arc shaped cams and straight cams are sized, shaped, and configured for engagement with said guide member arcs during eccentric rotation of rotor assembly.
Alternatively, a rotor with an even number of eight or more straight cam surfaces arranged about a rotor assembly center longitudinal axis; the straight cams having orientation such that half the straight cam surfaces radially oppose the remaining half of the straight cam surfaces;
straight edges being parallel to line perpendicular to longitudinal axis of eccentric portion of shaft at a distance of Rp;
a rotor guide assembly extending from at least one of said end walls, the rotor guide assembly having four or more arc shaped cams, half of said arc shaped cams radially oppose remaining arc shaped cams, a distance from said shaft center longitudinal axis to each of said arc center longitudinal axes being equal to an offset distance RC2, said rotor guide member assembly including cam surfaces extending in parallel fashion through one of said parallel end faces for engagement with said eight or more straight cams during said eccentric rotation of said rotor assembly, each of said guide members having a surface with a partially circular perpendicular cross-sectional shape over a portion thereof which engages said straight cam, rotor guide member assembly having approximately half of guide member arcs radially opposing remaining guide member arcs, both sets of opposing guide member arcs having maximum angle between adjacent circular arc longitudinal center of greater than 180 degrees; and
wherein each of said arc shaped cams and straight cams are sized, shaped, and configured for engagement with said guide member arcs during eccentric rotation of rotor assembly.